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Finding and fixing a tripping circuit in London costs £80 to £150 for the first hour on a weekday and £60 to £80 an hour after that; most faults are traced and fixed within one to two hours, so £100 to £250 is the usual bill. If the fault is the board itself, a replacement runs £500 to £900.
| Job | London low | London typical | London high | UK typical | What moves the price |
|---|---|---|---|---|---|
| Daytime fault-finding visit, first hour | £80 | £100 | £150 | £115 | Includes the diagnosis; parts extra |
| Each further hour, daytime | £60 | £70 | £80 | £55 | Hidden cable faults take longer than a faulty appliance |
| Evening or weekend, first hour | £90 | £110 | £150 | 1.5 to 2 times the day rate | |
| Night emergency, first hour | £100 | £150 | £200 | £90 | Only if it will not reset and you have no power |
| Replace a faulty RCD or breaker, fitted | £80 | £120 | £200 | The device is £8 to £40; the rest is the visit | |
| Replace the whole board, if that is the fault | £500 | £700 | £900 | £450 | Rewireable fuses, no RCD or a damaged board |
A circuit trips because something on it is leaking current or drawing too much: a faulty appliance, moisture in an outdoor socket or a bathroom light, a nail through a cable, an overloaded ring, or an ageing RCD that has become too sensitive. The tripping is the protection working, not the fault itself, which is why resetting it again and again does not help and can hide a real problem.
You can safely do three things: note which switch trips, unplug everything on that circuit and reset it once, and plug things back in one at a time to see what trips it. If it trips with nothing plugged in, or the main switch trips, stop there. Do not open the consumer unit.
The electrician isolates circuits one by one and tests the insulation of each until the fault shows itself; a faulty appliance or a wet fitting is found in the first hour, a damaged cable in a wall can take two or three. Where the board is the problem, with rewireable fuses, no RCD or a C2 on an EICR, the honest fix is a new consumer unit, common in London flats with 1990s or older boards.
Prices last checked: September 2026. Based on the published 2026 tariffs of four London electrical firms and the board and device prices on three London price pages. PROS AI does not yet have enough completed fault-finding jobs in London to publish its own averages.
Nine times out of ten an appliance is leaking current: a kettle, washing machine, fridge or an outdoor light that has taken in water. Unplug everything on the circuit, reset once, and reconnect one item at a time. If it trips with nothing connected, the fault is in the fixed wiring or the RCD itself, and that is a visit.
£80 to £150 for the first hour on a weekday, which covers the diagnosis for most faults, then £60 to £80 an hour. A typical bill is £100 to £250. Evenings and weekends run 1.5 to 2 times that, and a night call-out is £100 to £200 for the first hour.
You can reset a tripped RCD or breaker once and isolate the appliance that causes it. You cannot legally or safely go further: opening the consumer unit, replacing a breaker or working on a circuit in a bathroom is electrician's work under Part P, and a wrong move on a live board is how people get hurt.
One hour for an appliance or a wet fitting, two to three for a cable fault behind plaster or under a floor. A good electrician tells you after the first hour whether it is found, and quotes the repair before doing it.
When the board still has rewireable fuses, has no RCD protection at all, trips on more than one circuit for no pattern, shows heat marks, or an EICR has coded it C2. Then a new board is the fix, £500 to £900 for most London homes, and the tripping circuit gets tested as part of that job.
Written by Shay Hazan, PROS AI.
£80 - £300call-out + hourly
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